Metastatic adenocarcinoma in dogs, particularly when it originates in the anal glands, represents a relatively rare form of cancer, accounting for only about 2% of all skin tumors in dogs. While conditions like impaction, succulitis, and abscessation are more frequently encountered in dogs than malignancy, the rarity of metastatic adenocarcinoma does not diminish its seriousness.
It’s important to treat this condition with urgency and care if there is a suspicion of its presence. Despite being less common, it remains a significant health concern that requires prompt and thorough attention from veterinary professionals.
Where Are the Anal Glands?
The anal glands are two small structures located under the skin on each side of your dog’s anus. The inner lining of each sac produces a substance that’s released through a small opening near the anus. If you’ve ever watched your dog scoot their butt across the floor and then smelled a potent, unpleasant odor, it’s likely some of this substance was released.
In normal situations, it’s released when your dog goes poop. The act of excretion causes pressure on these anal sacs. It’s like a biological scent marker that tells other animals, ‘hey, I was here.’ But sometimes, it can be released spontaneously, especially when dogs are super excited or nervous.
Anal Gland Cancers in Dogs
The most common type of cancer in the anal glands is known as anal sac adenocarcinoma. You may also hear this referred to as apocrine gland anal sac adenocarcinoma. For those new to the world of cancer, this condition is abbreviated as AGASACA.
Breeds Prone to Apocrine Gland Adenocarcinoma
The breeds commonly affected by this type of malignant tumor include Cavalier King Charles Spaniels, English Springer Spaniels, German Shepherds, Dachshunds, and Golden Retrievers. Usually, it doesn’t occur until dogs are about 10 years of age (although it could occur sooner). Males and females are both prone to this condition; there is no difference with regard to gender.
Signs of Apocrine Adenocarcinoma in Dogs
Some dogs may not show signs, but it will still be diagnosed during your dog’s fecal exam at their annual checkup. Other dogs do experience signs like lethargy, constipation (straining to defecate), vomiting, increased thirst, weakness in the hind limbs, or a mixture of all of these.
Diagnosing an Anal Sac Tumor as Anal Sac Adenocarcinoma (AGASACA)
As we said above, your vet may find this tumor while performing your dog’s routine rectal examination. During this period, they will also check the regional lymph nodes for swelling. With this condition, blood tests and urine tests often come back normal, but they may notice elevated calcium levels in the blood (also indicative of kidney disease in dogs).
A sample of the mass will be taken using a fine needle aspirate. It will then be examined under a microscope (AGASACA cytology) to determine if the cells are suspected of being cancerous. However, a biopsy should be taken to obtain a definitive diagnosis. This may be done by having the mass surgically removed or by having surgery to remove just a small portion of the mass.
Other tests include radiographs of the chest or an abdominal ultrasound. During the ultrasound, the vet will want to see if the cancer has spread to other parts of the body.
Once the cancer is discovered, tumors can be found in the lungs in 2-13% of dogs. In 50% of malignancies, cancerous cells will also be found in the abdomen. The veterinarian may also choose to run a CT scan or MRI for diagnosis.
Treatment Options for Dogs with Anal Gland Adenocarcinomas
If your dog is diagnosed with hypercalcemia, they may need to be stabilized using IV fluids and medications. Following this treatment, these are the conventional options:
Surgery in Dogs Affected by APASACA
Your vet may recommend surgery to remove to remove the mass as well as the anal sac. This is often the treatment of choice by many vets. Complete removal may be challenging if your dog has a larger mass since it’s so close to the rectal area, and there could be surgical complications like fecal incontinence (may be permanent or temporary) or infections.
If there are enlarged lymph nodes, they may also be removed. It’s important to note here, though: the risk of hemorrhage with this procedure is high, and nerve damage caused by removal could lead to urinary incontinence. Complications occur in about 10% of cases.
Radiation Therapy for Apocrine Gland Carcinoma
Radiation therapy may be used before, throughout, or post-surgery for the mass and enlarged lymph nodes. This is often used in cases where the complete removal of the mass or lymph nodes is not possible or where it would significantly decrease your dog’s quality of life. It may also be used for palliative (comfort) purposes. Life-threatening complications could also occur with this option.
Chemotherapy for Apocrine Gland Carcinoma (Dog)
Chemo has not proven to improve the AGASACA prognosis in dogs. But it may lead to some benefit when combined with radiation therapy.
Canine Adenocarcinoma Life Expectancy With Treatment
The ultimate question here is, ‘what is the life expectancy of a dog with rectal cancer?’ Factors affecting how long dogs live with perianal adenocarcinoma without treatment or even with treatment include the size of the tumor, how much the lymph nodes are affected, if the cancer has spread to other regions of the body, and what their treatment protocol involves.
According to the Canine Health Center at Cornell University, their research has found:
- “Some dogs may experience an average survival time of more than 3 years.
- Recurrence of tumor at the surgical site occurs in up to 45% of cases.
- Tumors less than 2.5 centimeters in size have a better prognosis.
- Dogs without enlarged lymph nodes or other metastases have a better prognosis.
- Dogs with enlarged lymph nodes have improved survival times if the lymph nodes are also removed.
- Dogs with hypercalcemia have a shorter average survival time.
- Radiation therapy can improve clinical signs and survival time. “
Reducing the Risks Associated with Apocrine Gland Adenocarcinoma in Dogs
There’s no sure-fire way to prevent this condition, but you can reduce your dog’s risk of it spreading by having them checked regularly by your veterinarian and feeding your dog a healthy diet.
Consider a Switch to Raw
Before you make any sort of nutritional change, pay attention to your dog’s poop. I know it sounds weird, but trust me, it’s important (not only for this condition but for tons of others).
If their poop is too soft most of the time, they are more likely to experience problems with their anal glands. In these cases, you can switch to a raw food diet and add in some extra bone. You don’t need to add a lot, but my dog personally loves turkey and chicken necks (as do many of our clients’ dogs).
If you’re already feeding a raw diet, add in a little extra bone. Remember, you don’t want to add too much. If your dog’s poop becomes too hard, reduce the amount of bone in the diet. If your pup is allergic to chicken or turkey, oxtail can also provide them with an easily digestible form of bone.
First of all, you need to pay attention to your dog’s poops. If they’re too soft, and you can easily tell, they’re more likely to have anal gland issues.
Supplement Options for Dogs With Anal Gland Issues
If you’re looking for a supplement to help with anal gland issues, we highly recommend you visit your veterinarian so they’re able to monitor your dog while on these. The supplements that may be used by a holistic veterinarian include silica (to excrete anything foreign), arnica, aconite, hepar sulph, or a mixture of all of these.
If you see that your dog is uncomfortable, you can apply a warm compress containing green tea to soothe their anus (if they will allow you to). The heat may help release some of the fluid in their anal glands.
If you have something in particular that has worked for your dog with anal gland issues, we’d love for you to share it in our Facebook group here.
For further reading, we recommend:
https://www.veterinarycancer.com/anal-gland-adenocarcinoma